It's more forgiving with caps because you can line the inside with phenolic.The challenge with using antler material for joints and butt caps is finding pieces with a more solid center. They tend to be soft and pithy on the inside.
1 1/8 for joints gives you lots of room to play. Pith not more than 9/16 preferably.To get a functional joint and butt cap from Antlers, how thick would these need to be?